What's in Brian's Brain?

Of all the computing devices I encounter from day to day, the most mysterious is the one in my own head. Other machines—from gadgets in my pocket to unseen Internet servers—process information in ways that I think I understand. When it comes to the brain, however, I haven’t got a clue.

Filling in the blanks in our knowledge of the brain is the mission of several ongoing and recently announced research programs. The Allen Institute for Brain Science in Seattle has been compiling atlases of nerve tissue. At Harvard University the Connectome Project is tracing the links between individual nerve cells. The similarly named Human Connectome Project, a collaboration of four institutions, looks at the brain’s wiring diagram on a larger scale.

“Functional connectomics” would go a step beyond circuit diagrams to active wiretapping—listening in on the signals that pass through all the nerve fibers in a network. A project of this kind called the Brain Activity Map has become the centerpiece of a program announced in April by President Barack Obama, with the promise of $100 million in first-year federal funding.

Meanwhile the European Commission has committed €1 billion ($1.3 billion) over 10 years to the Human Brain Project, which emphasizes computational models of nervous-system activity. It will build on an existing simulation called the Blue Brain Project.

The questions addressed by these endeavors are so intriguing—and our present ignorance of how the brain works is so irksome—that I find myself rooting enthusiastically for the programs’ success. Yet some of the questions are also so difficult that it’s hard to set aside skepticism.